In this study, a radiation detection system consisting of two cerium doped lanthanum bromide (LaBr 3:Ce) scintillation detectors in a gamma-gamma coincidence configuration has been used to demonstrate the advantages that coincident detection provides relative to a single detector, and the advantages that LaBr 3:Ce detectors provide relative to high purity germanium (HPGe) detectors. Signal to noise ratios of select photopeak pairs for these detectors have been compared to high-purity germanium (HPGe) detectors in both single and coincident detector configurations in order to quantify the performance of each detector configuration. The efficiency and energy resolution of LaBr 3:Ce detectors havemore » been determined and compared to HPGe detectors. Coincident gamma-ray pairs from the radionuclides 152Eu and 133Ba have been identified in a sample that is dominated by 137Cs. Gamma-gamma coincidence successfully reduced the Compton continuum from the large 137Cs peak, revealed several coincident gamma energies characteristic of these nuclides, and improved the signal-to-noise ratio relative to single detector measurements. LaBr 3:Ce detectors performed at count rates multiple times higher than can be achieved with HPGe detectors. The standard background spectrum consisting of peaks associated with transitions within the LaBr 3:Ce crystal has also been significantly reduced. Finally, it is shown that LaBr 3:Ce detectors have the unique capability to perform gamma-gamma coincidence measurements in very high count rate scenarios, which can potentially benefit nuclear safeguards in situ measurements of spent nuclear fuel.« less

The performance of new scintillator detectors based on LaBr{sub 3}(Ce) technology was evaluated in conjunction with the Gammasphere spectrometer. Specifically, the lifetimes of states between 50 ps and 1 ns, populated in the decay of the {sup 177m}Lu isomeric state (T{sub 1/2} = 160 d), have been measured. Even though the decay scheme is rather complex, it is possible to perform precise measurements because of the superior energy resolution of the LaBr{sub 3}(Ce) detectors, compared to that of BaF{sub 2} scintillators, when used in combination with the power of the Gammasphere array to isolate a specific {gamma} cascade

Commercially available LaBr{sub 3}:5% Ce{sup 3+} scintillators show with photomultiplier tube readout about 2.7% energy resolution for the detection of 662 keV {gamma}-rays. Here we will show that by co-doping LaBr{sub 3}:Ce{sup 3+} with Sr{sup 2+} or Ca{sup 2+} the resolution is improved to 2.0%. Such an improvement is attributed to a strong reduction of the scintillation light losses that are due to radiationless recombination of free electrons and holes during the earliest stages (1-10 ps) inside the high free charge carrier density parts of the ionization track.